Combined ventilating louver and back draft damper

ABSTRACT

A back draft air damper is incorporated within a ventilating louver with pivotally mounted damper blades movable between a closed position in which the damper blades restrict air flow in a reverse direction and an open position in which the damper blades permit a substantial flow of air in a forward direction between fixed ventilating louver blades. Each damper blade has a lower seal for engaging a next lower louver blade and surfaces along each vertical side thereof to seal against a vertical side frame member. The damper blades are hinged along their upper edges to a louver blade thereabove to provide a sealed relationship at the top of the damper blades.

United States Patent Tarnoff 15] 3,682,084 [451 Aug. 8,1972

1541 COMBINED VENTILATING LOUVER- AND BACK DRAFT DAMPER I 72 Inventor:Sherwin s. Tarnofi, Northbrook, 111. [73] Assignee: Air Balance, l n c.,Chicago, lll.v 221 Filedz Feb. 16,1970

[21] Appl. No.: 11,726

Belden .....98/12l R x 3,422,744 -l/l969 Tarnoff ..98/l2l R PrimaryExaminer-Meyer Perlin Assistant Examiner-W. C. AndersonAttorney-Anderson, Luedeka, Fitch, Even and Tabin [S7] ABSTRACT A backdraft air damper is incorporated within a ventilating louver withpivotally mounted damper blades movable between a closed position inwhich the damper blades restrict air flow in a reverse direction and anopen position in which the damper blades permit a substantial flow ofair in a forward direction between fixed ventilating louver blades. Eachdamper blade has a lower seal for engaging a next lower louver blade andsurfaces along each vertical side thereof to seal against a verticalside frame member. The damper blades are hinged along their upper edgesto a louver blade thereabove to provide a sealed relationship at the topof the damper blades.

sclairmADrawingl igur-es COMBINED VENTILATING LOUVER AND BACK DRAFIDAMPER This invention relates to ventilating louvers, particularly toventilating louvers incorporating air dampers and having fixed louverblades and movable damper blades, and more particularly to back draftdampers in which the damper blades are movable between an open positionin which air flows through the ventilating louver and a closed positionin which air is prevented from flowing through the louver.

Back draft dampers are designed to allow air to flow in a firstdirection as, for example, from the interior of a building, and topreclude air flow in the opposite direction as, for example, into theinterior of the building. It is particularly desirable that the damperpreclude a substantial air flow in the wrong direction at highvelocities which would transport rain, snow or other foreign matter intothe building. In some installations, the movable blades are designed toshift to the closed position when the air pressure differential in thereverse direction reaches a predetermined level, as during a wind storm.In other installations, the damper blades are shifted by a mechanicalactuator between open and closed positions.

Of particular significance to a commercially acceptable ventilatinglouver incorporating a back draft damper is that it can be formed in acompact size of relatively few and simple components which are readilyassembled to provide a low cast assembly. In addition to size and cost,it is important to provide a good seal to air flow in reverse direction,particularly at high velocities which can transport rain or snow.

Accordingly, an object of the invention is to provide an improvedventilating louver incorporating a back draft damper.

Other objects and advantages of the invention will become apparent fromthe following detailed description taken in connection with theaccompanying drawings in which:

FIG. 1 is a perspective view of a combined ventilating louver and airdamper embodying the novel features of the invention;

FIG. 2 is an enlarged, cross-sectional view of an upper comer of theassembly of FIG. 1;-

FIG. 3 is a fragmentary cross-sectional view in perspective illustrativeof the connection of fixed and movable louver blades to a rigid framefor the damper shown in FIG. 1; and

FIG. 4 is an enlarged sectional view of a portion of another embodimentof the invention shown in FIG. 2 in which movable louver blades arepositioned at open and closed positions by a mechanical actuator.

As shown in the drawings for purposes of illustration, the invention isembodied in a ventilator unit combining a ventilating louver and a backdraft damper of the type used for building ventilation, usually for ex-'hausting smoke or air from the building interior. The

ventilating louver is usually secured in an upright posinication with anair duct (not shown) which leads to outside atmosphere at a front side18 of the louver. A ventilating louver of this general kind is shown inUS. Pat. No. 3,422,744.

In accordance with the present invention, an air damper is incorporatedwith the ventilating louver to provide a combined unit 10 which may beeasily assembled, relatively trouble free in operation and produced inlarge quantities at a low cost. Also, as will be explained in greaterdetail hereinafter, the back draft damper of the present inventioncomprises damper blades 21 that restrict the reverse air flow not onlyat the area of the blades themselves and along lower seals 23 betweenthe lower edges of the damper blades and a portion of the next lowerlouver blades 15 through a portion of the next lower louver blades butalso along vertical side seal areas 24 at which the damper blades havesealing relationships with vertically extending side flanges 25, as bestseen in FIG. 3, along the rear edges of the side members 27 of the rigidframe 13. In operation, the usual exhaust air pressure is sufficient toswing the damper blades 21 upwardly from a closed position, asillustrated in the solid lines of FIG. 2 to an open position, asillustrated in phantom lines of FIG. 2, and to maintain the damperblades in the open position to permit a substantial flow of air throughthe air passageways l7 and from the ventilating louver. On the otherhand, a gust of high velocity air in the opposite direction, as during awind storm or rain storm, will exert sufiicient pressure on the damperblades in the opposite direction to swing the damper blades 21 to aclosed sealed position to block the flow of air and hence rain, snow,etc. into the duct and into the interior of the building.

Referring now in greater detail to the individual elements of theventilating louver, the rigid frame 13 is preferably rectangular inshape and formed with a pair of opposite parallel vertical side members27 which are joined at the upper ends thereof to a horizontally disposedtop member 29 and at the bottom edges thereof to a horizontally disposedbottom member 31. These frame members thus encompass a rectangularframework with a rectangular opening into which are fitted the fixedlouver blades 15 and the damper blades 21. The rigid frame also definesa frame plane, which is usually vertical, with the fixed louver blades15 mounted in the frame inclined downwardly and forwardlyto prevent rainor snow from being carried therethrough. The frame has a narrow front torear profile as the damper blades are pivoted within the frame and noportions of these blades can swing outwardly of the frame.

For the purpose of interlocking the fixed louver blades 15 to the sidemembers 27 without the use of fasteners and in a quick and easy manner,it is preferred that each of the side members be provided with twovertically extending rails 33 and 34 which project inwardly and whichare integral with a wall 35 of the side member 27. Each of the rails 33and 34 is aligned with a corresponding rail 33 or 34 of the oppositeside member 27 in a vertical plane, and these respective vertical planesare disposed parallel to one another. The preferred interlockingarrangement between the fixed louver blades and the side members isaccomplished by having a number of slots 37 formed in the I rails 33 and34 to receive therein the ends of the fixed blades. More specifically,the slots 37 in one rail 33 are spaced apart in the vertical directionand are spaced of the ventilating louver. More specifically, the sideseal flanges 25 project inwardly, i.e. toward each other, beyond theinward projection of the rails 33 and 34. With this arrangement, ends 39of the damper blades 21 may swing freely past the rails 33 and 34 whenswinging between the open or closed positions and still engage the sideflanges 25 to effect vertical side seals to the reverse direction flowof air.

Each frame side member 27 is also formed with a forward, verticallyextending flange 45, as best seen in FIG. 3, against which is abutted adown-tumed forward end 46 of each fixed blade to help prevent a fixedblade from sliding downwardly and forwardly and to provide additionalrigidity to the frame. Each of the fixed louver blades is also heldagainst sliding relative to the rails 33 and 34 by projections 47 and 49which extend on either side of the rails at the location of the slots37. The projections 47 and 49 also provide additional rigidity to thelouver. The projections 47 and 49 define therebetween a slot or openingwhich has walls converging to an upper wall which will rest on the rails33 and 34 in the slots 37.

The fixed louver blades 15 are inclined to the vertical and horizontalto shelter the interior of the duct. Unless wind driven at highvelocity, rain and snow falling on the louver blades 15 fall downwardlyand'outwardly along the upper surfaces 55 of the blades 15 to bedischarged externally of the building. The blades is ob scure theinterior of the ducts to the view, and also prevent a direct horizontalaccess for air, water or dust. Water is particularly damaging if allowedto enter into a duct, and for this reason it is preferred that fixedlouver blades have a first rain barrier 53 which projects generally in ahorizontal plane from a central part of the upper side 55 of each fixedblade. Water droplets being driven by the wind upwardly along the upperside 55 of a fixed blade 15 will be stopped and gathered at the lowerside of the rain barrier 53 to accumulate in sufficient quantities forflowing down the blade and from the louver. Also, the top portion 41 ofeach fixed blade has a forwardly and horizontally extending flange 57which acts as a second catch or rain barrier to prevent the driving ofwater up along the top portion of a fixed blade and into the interior ofthe building. The lower seal 23 for the damper blades 21 preferablyengages and edge or end 59 of the flange 57 of the fixed blades 15.

A preferred hinge means is provided by an integral, semi-circular,cross-sectioned hinge portion 61 of the fixed louver blade 15 and amating circular cross-sectioned hinge end 63 on the top edge of thedamper blade 21. The preferred hinge portion 61 is formed duringextrusion of the blade and extends downwardly and across the undersideof the fixed louver blade and has an interior curved surface generallycomplementary to a curve of the upper hinge end 63 on its associateddamperblade. The parts fit together loosely, the relative sizes of thehinged portions being such that the damper blades 21 will freely swingand will not usually become bound by corrosion, dirt or other foreignmatter. The hinge connection also serves as an air seal against flow ofair or moisture along the upper edges of the damper blades 21 into theinterior of the building.

Each damper blade 21 is mounted for free swinging movement and has alower seal 23 for sealing engagement with the horizontally disposedflange 57 of the fixed blade. More specifically, each damper bladepreferably carries a seal pad 69 of elastomeric, or resilient materialsuch as rubber or plastic for abutting the flange end 59 and providingtherewith a tight seal which is substantially moisture-proof andair-tight when the resilient seal pad 69 is urged under the force ofreversely directed air flow tightly against the edge 59 of a fixedlouver blade. The seal pad 69 is secured at the base 71 of a channel 73formed on the lower end of each damper blade. The upper side of thechannel 73 is defined by a forwardly extending web 75 which is parallelto and slightly above the fixed blade flange 57 and is integrallyattached to a vertically extending flat blade portion 77 which atits-lateral ends 39 may abut with the side seal flanges 25. The bladeportion 77 is the portion that covers the opening between successiveblades 15. In the closed position, this blade extends downwardlyrearwardly of the hinge to seal the opening. A blade section 79 extendsdownwardly and rearwardly from the hinge end 63 to connect the bladeportion 77 .to the hinge end 63, so that the latter may support theportion 77 for pivotal movement between the open and closed positions.The preferred manner of assembly is to insert one end of each louverblade into slots 37 in rails 33 and 34 of one frame side member with thelouver blades held by a jig in proper alignment relative to each otherand to the top and bottom frame members 29 and 31. Then the oppositeside member is positioned to receive the blade ends and is secured tothe top and bottom members to provide the completed unit.

As seen in FIG. 2, all of the closure elements of the damper blades 21are rearward of the rails 34 when the blades are in their closedposition. Because the damper blades 21 are loosely hinged by a hingeformed by sliding the hinge end 63 into the hinge portion 61 of a louverblade 15, the damper blades 21 would be free to slide behind the rails34 and become locked in the closed position but for a stop 80 extendingoutwardly from each damper blade 21. The stop 80 extends outwardlybetween opposing rails 34 and keeps the blade 21 centered between therails, permitting free swinging of the damper blade past the rails butpreventing longitudinal sliding of the hinge end 63 relative to thestationary hinge the damper 61 of its associated fixed blade 15. I

The damper blades 21 may be sufficiently light in weight that airleaving the building under slight pressure pushes the damper blades totheir open position.

Ordinarily, the pressure and velocity of the air is sufficient to pushthe damper blades to the position shown by phantom lines in FIG. 2,where the damper blades 21 are stopped by the respective stops 80striking the underside of the fixed blade 15 thereabove.

Upon the occurrence of a back draft, as when the wind blows morestronglyagainst the outside of the louver than the exhaust air withinthe building is blowing against the inside of the louver, the damperblade 21 fall toward their closed positions under the force of gravityand are pushed into their closed positions by the greater externalpressure. In the closed position, the unit is entirely sealed againstthe entry of rain, snow, etc.

For some installations it is preferred that the damper blades 21 bepositively controlled and shifted at will. Rather than having thedampers closed by gravity and air pressure, the dampers are closed by anoperator when required by conditions, such as rain. As shown in FIG. 4,an actuating means 81 may be used to move the damper blades 21 betweenopen and closed positions rather than relying on air pressuredifferentials. More specifically, the actuating means 81 includes aseries of cranks 83, each crank being connected at its lower end 85 tothe rear of a respective damper blade 21 and pivotally mounted at itsopposite end on a pivot pin 87 fixed to a vertically movable actuatingrod 89. The actuating cranks are each formed with a pair of spaced arms91 between which is inserted the actuating rod with the pivot pin 87projecting through openings 93 in the respective arms 91. By raising theactuating rod 89 and the pivot pins, the damper blades 21 are swung in acounterclockwise direction to the closed position, as shown in solidlines in FIG. 4, in which the seal pads 69 on the damper blades 21engage the fixed blade flange ends 59 and in which the lateral ends 39of the damper blades are in sealing engagement with the side flanges 25of the rigid frame 13. Conversely, by pulling down on the actuating rod89, the crank arms 91 pivot clockwise on pivot pins 87 and force thedamper blades 21 to pivot about their respective axes through the hingeportions 61 of the fixed blades 15, until the stops 80 of damper bladesabut the fixed blades thereabove.

From the foregoing, it is seen that the present invention provides aninexpensive combined back draft damper and ventilating louver unit whichis formed of relatively few and simple parts and which may be readi lyassembled without the use of fasteners or other connecting devices. Thesealing engagement along the vertical sides of the damper blades and thevertical side flanges of the rigid frame and between resilient pad sealsand fixed blades results in a substantial blocking of a reverselydirected flow of high velocity air which would otherwise carry moistureor other foreign material into the interior of a duct leading into thebuilding.

While a preferred embodiment has been shown and described, it will beunderstood that there is no intent to limit the invention by suchdisclosure, but, rather, it is intended to cover all modifications andalternate constructions falling within the spirit and scope of theinvention. For example, although a single ventilating louver isillustrated, it is contemplated that four such louvers be mounted as thefour sides of a penthouse atop a building, so that the louver facing thewind may be closed while leaving the others open for ventilation.

l. A combined ventilating louver and back draft damper unit comprising arigid frame having parallel, vertical side members and defining anopening through which air may flow, a plurality of fixed louver bladesspanning said opening and joined to said side members, said fixed lowerblades being spaced vertically from each other to define air passagewaystherebetween and extending downwardly and forwardly from upper, rearwardportions thereof, a plurality of damper blades pivotally mounted forswinging between an opening position in which air may flow through saidpassageways in a forward direction and a closed position in which saidblades substantially close said passageways to air flow in a reversedirection, a lower seal on said damper blades for swinging into sealingengagement with a fixed louver blade therebeneath when said damperblades are in said closed position, said vertical side members of saidframe having vertically extending and inwardly projecting side sea]flanges adjacent the rear of said ventilating louver, hinge meanspivotally mounting said damper blades on the undersides of said fixedblades at positions forward of said side seal flanges, said hinge meanscomprising interlocking hinge portions on the respective damper andlouver blades assembled by axial sliding of one relative to the other,said damper blades having portions extending in a rearward directionfrom said interlocking hinge portions and then extending downwardly toprovide surfaces disposed relative to said side seal flanges for sealingengagement therewith when said damper blades are in said closedposition.

2. A unit in accordance with claim 1 in which vertically extending railsare provided on said side members and have portions interfitted withsaid fixed louver blades and in which stop means on said damper bladescenter the same between said rails to limit longitudinal slidingmovement of said movable blades relative to said fixed louver ventilatorblades.

3. A unit in accordance with claim 1 in which rain barriers havinghorizontally extending flanges are formed on the upper portion of saidfixed blades and are disposed for sealing engagement with said lowerseals.

4. A unit in accordance with claim 1 in which said lower seal includes aresilient seal pad carried on the lower'end of said damper blades toabut said fixed blade flanges.

5. A combined ventilating louver and back draft damper unit comprising arigid frame having parallel, vertical side members and defining anopening through which air may flow, a plurality of fixed louver bladesspanning said opening and joined to said side member, verticallyextending rails projecting inwardly from said vertically extending sidemembers and interfitted with said fixed louver blades and spacing thesame vertically from each other to define air passageways therebetween,said fixed louver blades extending downwardly and forwardly from upper,rearward portions thereof, a plurality of damper blades, hinge means onthe undersides of said fixed blades for pivotally mounting said damperblades for swinging between an open position in which air may flowthrough said passageways in a forward direction and a closed position inwhich said blades substantially close said passageways to air flow in areverse direction, said then extending downwardly and having surfacesdisposed relative to said side seal flanges for sealing engagementtherewith when said damper blades are in said closed position, saiddamper blades having stop means thereon projecting forwardly therefrombetween and adjacent an opposing pair of said inwardly projectingrailsto continuously limit axial sliding of said hinge portions relative toone another.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIGN Patent No. 3 r r084 Dated August 8 I 1972 Invent0r(s) Sherwin S. Tarnoff It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Column 1, line 31, change "cast" to -cost--;

Column 2, lines 14 and 15, delete through a'portion of the next lowerlouver blades";

Column 3, line 59, change "and" to --an;

Column 4, line 58, change "the damper" to portion-;

Column 5, line 4, change "blade" to -blades---;

Column 5, line 7, after "external" insert --air-;

Column 5, line 21, after "opposite" insert --upper-;

Claim 1, line 6 change "lower" to -louver;

Claim 1, line 10, change "opening" to --open;

Claim 4, line 4, change "blade flanges" to elouver blades.

Signed and sealed this 23rd day of January 1973..

(SEAL) Attest:

ROBERT GOTTSCHALK RD M.FLETCHER JR. EDWA Commissioner of PatentsAttesting Officer FORM USCOMM-DC 60376-P69 U,5. GOVERNMENT PRINTINGOFFICE: I969 0"365'335,

1. A combined ventilating louver and back draft damper unit comprising arigid frame having parallel, vertical side members and defining anopening through which air may flow, a plurality of fixed louver bladesspanning said opening and joined to said side members, said fixed lowerblades being spaced vertically from each other to define air passagewaystherebetween and extending downwardly and forwardly from upper, rearwardportions thereof, a plurality of damper blades pivotally mounted forswinging between an opening position in which air may flow through saidpassageways in a forward direction and a closed position in which saidblades substantially close said passageways to air flow in a reversedirection, a lower seal on said damper blades for swinging into sealingengagement with a fixed louver blade therebeneath when said damperblades are in said closed position, said vertical side members of saidframe having vertically extending and inwardly projecting side sealflanges adjacent the rear of said ventilating louver, hinge meanspivotally mounting said damper blades on the undersides of said fixedblades at positions forward of said side seal flanges, said hinge meanscomprising interlocking hinge portions on the respective damper andlouver blades assembled by axial sliding of one relative to the other,said damper blades having portions extending in a rearward directionfrom said interlocking hinge portions and then extending downwardly toprovide surfaces disposed relative to said side seal flanges for sealingengagement therewith when said damper blades are in said closedposition.
 2. A unit in accordance with claim 1 in which verticallyextending rails are provided on said side members and have portionsinteRfitted with said fixed louver blades and in which stop means onsaid damper blades center the same between said rails to limitlongitudinal sliding movement of said movable blades relative to saidfixed louver ventilator blades.
 3. A unit in accordance with claim 1 inwhich rain barriers having horizontally extending flanges are formed onthe upper portion of said fixed blades and are disposed for sealingengagement with said lower seals.
 4. A unit in accordance with claim 1in which said lower seal includes a resilient seal pad carried on thelower end of said damper blades to abut said fixed blade flanges.
 5. Acombined ventilating louver and back draft damper unit comprising arigid frame having parallel, vertical side members and defining anopening through which air may flow, a plurality of fixed louver bladesspanning said opening and joined to said side member, verticallyextending rails projecting inwardly from said vertically extending sidemembers and interfitted with said fixed louver blades and spacing thesame vertically from each other to define air passageways therebetween,said fixed louver blades extending downwardly and forwardly from upper,rearward portions thereof, a plurality of damper blades, hinge means onthe undersides of said fixed blades for pivotally mounting said damperblades for swinging between an open position in which air may flowthrough said passageways in a forward direction and a closed position inwhich said blades substantially close said passageways to air flow in areverse direction, said hinge means comprising interlocking hingeportions on the respective damper and louver blades, a lower seal onsaid damper blades for sealing engagement with a fixed louver bladetherebeneath when said damper blades are in said closed position, saidvertical side members of said frame having inwardly projecting side sealflanges adjacent the rear of said ventilating louver and locatedrearwardly of said hinge means, said damper blades having portionsextending in a rearward direction from said interlocking hinge portionsand then extending downwardly and having surfaces disposed relative tosaid side seal flanges for sealing engagement therewith when said damperblades are in said closed position, said damper blades having stop meansthereon projecting forwardly therefrom between and adjacent an opposingpair of said inwardly projecting rails to continuously limit axialsliding of said hinge portions relative to one another.